#!/bin/bash
#
# funccount - count kernel function calls matching specified wildcards.
#             Uses Linux ftrace.
#
# This is a proof of concept using Linux ftrace capabilities on older kernels,
# and works by using function profiling: in-kernel counters.
#
# USAGE: funccount [-hT] [-i secs] [-d secs] [-t top] funcstring
#    eg,
#        funccount 'ext3*'	# count all ext3* kernel function calls
#
# Run "funccount -h" for full usage.
#
# WARNING: This uses dynamic tracing of kernel functions, and could cause
# kernel panics or freezes. Test, and know what you are doing, before use.
#
# REQUIREMENTS: CONFIG_FUNCTION_PROFILER, awk.
#
# From perf-tools: https://github.com/brendangregg/perf-tools
#
# COPYRIGHT: Copyright (c) 2014 Brendan Gregg.
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
#  (http://www.gnu.org/copyleft/gpl.html)
#
# 12-Jul-2014	Brendan Gregg	Created this.

### default variables
setglobal tracing = '/sys/kernel/debug/tracing'
setglobal opt_duration = '0'; setglobal duration = ''; setglobal opt_interval = '0'; setglobal interval = '999999'; setglobal opt_timestamp = '0'
setglobal opt_tail = '0'; setglobal tcmd = 'cat'; setglobal ttext = ''
trap 'quit=1' INT QUIT TERM PIPE HUP	# sends execution to end tracing section

proc usage {
	cat << """ >&2
USAGE: funccount [-hT] [-i secs] [-d secs] [-t top] funcstring
                 -d seconds      # total duration of trace
                 -h              # this usage message
                 -i seconds      # interval summary
                 -t top          # show top num entries only
                 -T              # include timestamp (for -i)
  eg,
       funccount 'vfs*'          # trace all funcs that match "vfs*"
       funccount -d 5 'tcp*'     # trace "tcp*" funcs for 5 seconds
       funccount -t 10 'ext3*'   # show top 10 "ext3*" funcs
       funccount -i 1 'ext3*'    # summary every 1 second
       funccount -i 1 -d 5 'ext3*' # 5 x 1 second summaries

See the man page and example file for more info.
"""
> !2
USAGE: funccount [-hT] [-i secs] [-d secs] [-t top] funcstring
                 -d seconds      # total duration of trace
                 -h              # this usage message
                 -i seconds      # interval summary
                 -t top          # show top num entries only
                 -T              # include timestamp (for -i)
  eg,
       funccount 'vfs*'          # trace all funcs that match "vfs*"
       funccount -d 5 'tcp*'     # trace "tcp*" funcs for 5 seconds
       funccount -t 10 'ext3*'   # show top 10 "ext3*" funcs
       funccount -i 1 'ext3*'    # summary every 1 second
       funccount -i 1 -d 5 'ext3*' # 5 x 1 second summaries

See the man page and example file for more info.
END
	exit
}

proc warn {
	if ! eval @Argv {
		echo >&2 "WARNING: command failed \"$ifsjoin(Argv)> !2 "WARNING: command failed \"$@\""
	}
}

proc die {
	echo >&2 @Argv> !2 "$@"
	exit 1
}

### process options
while getopts d:hi:t:T opt
{
	match $opt {
	with d	setglobal opt_duration = '1'; setglobal duration = $OPTARG 
	with i	setglobal opt_interval = '1'; setglobal interval = $OPTARG 
	with t	setglobal opt_tail = '1'; setglobal tnum = $OPTARG 
	with T	setglobal opt_timestamp = '1' 
	with h|?	usage 
	}
}
shift $shExpr(' $OPTIND - 1 ')

### option logic
sh-expr ' $# == 0 ' && usage
setglobal funcs = $1
if sh-expr ' opt_tail ' {
	setglobal tcmd = ""tail -$tnum""
	setglobal ttext = "" Top $tnum only.""
}
if sh-expr ' opt_duration ' {
	echo "Tracing \"$funcs\" for $duration seconds.$ttext.."
} else {
	echo "Tracing \"$funcs\".$ttext.. Ctrl-C to end."
}
sh-expr ' opt_duration && !opt_interval ' && setglobal interval = $duration

### check permissions
cd $tracing || die "ERROR: accessing tracing. Root user? Kernel has FTRACE?
    debugfs mounted? (mount -t debugfs debugfs /sys/kernel/debug)"

### enable tracing
sysctl -q kernel.ftrace_enabled=1	# doesn't set exit status
echo $funcs > set_ftrace_filter || die "ERROR: enabling \"$funcs\". Exiting."
warn "echo nop > current_tracer"
if ! echo 1 > function_profile_enabled {
	echo > set_ftrace_filter
	die "ERROR: enabling function profiling."\
	    "Have CONFIG_FUNCTION_PROFILER? Exiting."
}

### summarize
setglobal quit = '0'; setglobal secs = '0'
while sh-expr ' !quit && (!opt_duration || secs < duration) ' {
	sh-expr ' secs += interval '
	echo 0 > function_profile_enabled
	echo 1 > function_profile_enabled
	sleep $interval

	echo
	sh-expr ' opt_timestamp ' && date
	printf "%-30s %8s\n" "FUNC" "COUNT"

	cat trace_stat/function* | awk '
	# skip headers by matching on the numeric hit column
	$2 ~ /[0-9]/ { a[$1] += $2 }
	END {
		for (k in a) {
			printf "%-30s %8d\n", k,  a[k]
		}
	}' | sort -n -k2 | $tcmd
}

### end tracing
echo !2 >/dev/null
echo "Ending tracing..." !2 >/dev/null
warn "echo 0 > function_profile_enabled"
warn "echo > set_ftrace_filter"